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Mathematics · 术语表

什么是 Collinearity?

又称: collinear vectors

Definition 6.9 High School Mathematics · 第 6 章 — Vectors

Two vectors u⃗\vec u and v⃗\vec v are collinear when they have the same direction, i.e. when v⃗=ku⃗\vec v = k \vec u for some real kk (or one of them is 0⃗\vec 0).

示例

Example 6.14

Are u⃗ (3,−2)\vec u\,(3, -2) and v⃗ (−6,4)\vec v\,(-6, 4) collinear? Compute ad−bc=3×4−(−2)×(−6)=12−12=0ad - bc = 3 \times 4 - (-2)\times(-6) = 12 - 12 = 0: yes, and indeed v⃗=−2u⃗\vec v = -2\vec u. For u⃗ (3,−2)\vec u\,(3, -2) and w⃗ (1,5)\vec w\,(1, 5): 3×5−(−2)×1=17≠03 \times 5 - (-2) \times 1 = 17 \neq 0: not collinear.

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